Enclosing casing for electrical control devices



Nov. 9, 1943. H. J. KocH ETAL l 2,334,012

ENCLOSING` CASING FOR ELECTRICAL CONTROL DEVICES Filed Nov. 6, 1941 Patented Nov. 9, 1943 ENCLOSING CASING FCR ELECTRICAL CONTROL DEVICES Herman J. Koch, Wauwatesa, and Anthony A. Kraus, Milwaukee, Wis., assigner: tov Gutier-V Hammer, Inc., Milwaukee, Wis., a. corporation of Delaware Application November 6, 1941, Serial No. 418354 9 Claims.

This invention relates to improvements in enclosing casings for electrical control devices. The invention relates more particularly to improvements in devices for releasably latching or fastening the covers of such `casings in closed position.

A primary object of the invention is to provide an improved and simplied manually operable latching device for clamping a casing cover in closed position-the elements of the latch being concealed.

Another object is to provide novel means for effecting manually controlled movement of the latch to and insuring retention thereof in either latching or unlatching position.

Another object is to provide novel and simple means for cooperation with the latching device or devices for rendering the enclosing casing substantially dust-tight.

Another object is to provide a novel form of casing and cover wherein a plurality of latcl'iingv devices may be utilized as the sole means for retaining the cover in assembled and closed position relatively to the casing.

Another object is to provide a novel arrangement of parts whereby the manual operating knobs of the latching devices are at all times readily accessible exteriorly of the walls of the casing.

Another and more specific object is to provide for complete removal of the cover or door of an enclosing casing of an electricalcontrol device, without the use of tools.

Another yobject is to generally improve the structural details and operating characteristics of cover latching devices of the aforementioned character. i

Another object is to provide a novel form oi casing and cover whereby the casings may be stacked or arranged close together (as in a cubicle panel or control center) without interfering with assembly or removal of the casing covers.

Another object is to provide casings and covers of neat and attractive appearance.

Other objects and advantages of the invention will hereinafter appear. p

The accompanying drawing illustrates certain embodiments of the invention which will now be described, it being understood` that the embodiments illustrated are susceptible of modication in respect of certain structural details thereof without departing from the invention as defined by the appended claims.

In the drawing,

llligure l is afragmentary view of a metal enclosing casing and cover having our improved cover latching or attaching device associated therewith-the casing and cover members being shown in section and the manually operable latch being shown in side elevation.

Fig. 2 is: a fragmentary view similar to Fig. l, but with most of the elements of the latching device also shown in section.

Fig. 3' is a fragmentary sectional view, on the line. 3-3 oi Fig. l.

Fig. 4- is a front elevational view, on a greatly reduced scale, of a sheet metal housing and cover forming an enclosingv casing for an electrical control device of any suitable form (not shown) and illustrating use ci' four or our improved latching devices to clamp the cover in closed position with respect to the housing, an end portion oi the cover being broken away to illustrate the relationship of the peripheral gasket with respect to the housing and cover.

Fig. 5. is a iront elevational view of a modication wherein the housing has a flanged cover hinged thereto, and a single latching device, of the character herein disclosed, is utilized to effeet retention o! the cover in closed position, a portion of the cover being broken away to illustrate the slightly diierent arrangement of the peripheral gasket.

Fig. 6 is a perspective view of the latch element shown in Figs. 1 to 3, and p Fig. 'I is a perspective view of the metal washer which is rotatable with the shank associated with the manual operating knob, and against which washer one end of the coiled compression spring is adapted to bear.

Referring rst to Figs. 1 to 4, 6 and '7, the numeral l0 designates` generally the peripheral wall of a sheet metal housing of rectangular contour; or the rectangular front end portion of one unit of a cubicle, or electrical control center of known form. In accordance with our invention there is preferably rigidly attached to each side and end wall of the housing i0., asy by spot-welding, the vertical portion Il of a sheet metal strip member of approximately 2.-iorm in transverse cross section, wherebyfiange portions lib extend inwardly in a common plane at right angles to the peripheral wall Ill and oiset. inwardly a predetermined distance from the outer edge illa of said peripheral wall.

Each of said members of Z-form includes a portion Ii extending a predetermined distance toward, but short of, the edge Hin of the peripheral wall i0 in substantially parallel relain Fig. 4. lThe upper 'edge of gasket I2 is preferably located inwardly of the edge Ill8L of wall I0 but forwardly of the edges of portions I Ic of said members of Z-form.

When it is desired to provide a substantially dust-tight fit or connection between the housing member and the cover member I3, the gasket I2V may be composed of felt or other suitable fibrous material. On the other hand, where the connection between the housing and cover I3 is to be made water-tight, the gasket I2 will preferably be composed of resilient or live rubber or a compressible rubber-like material.

As shown in Fig, 4, the hat sheet metal cover member I 3 is adapted to be freely inserted within the peripheral wall II)y of the housing; and as shown the sameis provided adjacent to each edge of the longer .sides thereof with a pair of substantially circular openings I3EL (Fig. 2). The openings I3 are adapted to` provide rotating clearance for the portion I4a of a stud or shank of hexagonal (or other polygonal) form in transverse cross section. ,Portion |4*- is provided ad-l jacent to its upper end with a reduced portion or neck Mb (Fig. 2) which provides for'positive anchorage thereof within afmanually operable knob .I 5. In practice we prefer to form the knob I5 of a zinc base metal alloy-which is die cast to the form-illustrated about the upper end of portion I4 of said shank,` thus rigidly uniting said parts.

Knob I5 comprises an upper finger grip portionv I5al of the contour best illustrated in Figs. 1, 4 and 5, which merges into alower portion I5b-of substantially circular contour. Portion I5b is provided in its lower surface with a substantially circular recess I5c (Fig. 42) which is adapted to accommodate av portionof the thickness of a washer I6, which is preferably composed or formed of felt, to provide a dust-tight gasket surrounding the respectively associated opening I3a (Fig. 2) lupon normal compression of washer I6 between the lower end of knob I5 and the upper surface of, cover'member I3. In practice washer I6 is made of greaterthicknessA at the central portion adjacent to opening I3, as shown at IIa in Figs` 1 and 2; andthe same` is also preferably provided witha central opening `I6b (Fig. 2) to afford rotatable clearance for shank portion Me. If it is desired to provide a'water-tight connection of the parts associated with the opening o-r openings |38, the washersY I6 may be composed of live or resilient rubber or a rubber-like material.

The portion I4i of the shank at the'inner sur'- face of cover member I3 is surrounded by a washer I'I, preferably formed of steel orl other suitable metal, having a central opening IIa (Fig. 2) affording rotatable clearance for said shank portion. A steel washer I8 underlies washer I'I, the Washer I8 having a hexagonal opening I8a (Fig. 7) to provide a close sliding but non-rotatable fit with Arespect to shank portion I4a. lSaid shank is provided with a lower end portion of re.- duced diameter which is threaded as y.shown at |46; and the extreme lower end portion of. said shankis still further reduced, as shown at Idd. Portion Md is provided with a peripheral groove planes below the common plane I4", which is adapted to receive a horseshoeshaped washer I9, preferably formed of steel.

Prior to attachment of washer I9 a coiled compression spring 20 is telescoped onto the shank portions MC, Illa, with one end thereof abutting washer I8. Thereupon the latching or clamping member 2| y-is threaded onto the shank portion |4. Member 2| preferably comprises a metal die casting of the form illustrated, the upper end 2| a of the body portion thereof being preferably of approximately diamond-shape and having its outer surfaces flaring in a downward direction until portions thereof meet or merge with the substantially centrally located bottom portion 2lb. Portion 2 IiL is provided with an upwardly opening recess 2|c of substantial depth, against the bottom wall' of which recess the other end of spring 20 is adapted to abut. Member 2| is provided with a tapped opening 2 Id (Fig 2) which is cenn trally alined with the bottom wall of said recess 2 Ic, saidtapped opening being adapted to accommodate the threaded shank -portion I4c to provide for adjustable relative movement `between said parts. After member 2| has been threaded onto shank portion Illc to a suflicient degree, the aforementioned washer I9 is attached, the latter acting to positively limit the degree of downward displacement `of member 2| relatively to the shank.

The two side surfaces 2|e and 2 If of member 2| are arranged at a predetermined angle to each other, whereby the same are selectively adapted to engage the vertical portion 22a of an angle ironQthe horizontal portion 22b of which is rigidly attached to the lower surface of cover member I3, as by spot welding. Said angle iron may be of just suflicient length for proper cooperation with one pair of the surfaces 2|e and 2If of a member 2|; but Where two or more of the latch members 2| are associated with a side of cover plate I3 (as in Fig. 4) we prefer to employ a singleT angle iron of a length to cooperate with the surfaces of all of the latch members associated with said side or edge portion of the cover member.

Each member 2| is provided with an integral laterally extending horizontal lug 2 Ig offset downwardly from the upper end thereof, said lug being preferably of the contour best illustrated in Figs. 3 and 6, wherein the convergent sides 2|h and 2|.1 merge with the straight side 2I-which side 2|j is adapted to abut the vertical portion IIa of the aforementioned Z-bar upon clockwise rotation of latch member 2| with respect to the casing or housing I0 (see Fig. 3).

Thus, with reference to Figs. 1 to 4, it may be assumed that prior tc insertion of cover I3 into the open end of the housing, as represented by peripheral wall I0, the knobs I5u have been rotated counterclockwise to effect movement of the latch members 2| inwardly of their respectivelyassociated shanks (as indicated in dotted lines at 2|x in Fig. 2) to such an extent that the lugs 2|I thereof are located in a plane or of the portions IIb of the Z-bars, it being understood that during such counterclockwise movement of the knobs thelatchmembers will likewise each have been moved counterclockwise to the extreme position thereof indicated in dotted lines Also, aswill be understood, in such extreme counterclockwise position of each latch member 2|l the lug 2|?. thereof will be so permit the same to clear its into engagement at 2|x in Fig. 3..

positioned as towith gasket I2. Thereafter upon clockwise rotation of each knob It'8L its associated latch member 2| will first be moved clockwise to the full line position thereof shown in Fig. 3, wherein it underlies thehorizontal portion IIb of its associated Z-bar; such initial clockwise movement of latch member 2I being insured-ln part by the fact that shank portion |45, washer I8 and spring 20 will tend to rotate clockwise as a unit, thus having a biasing effect upon the latch member ZI to also tend to effect clockwise rotation of the latter, and in part by the normal tendency kof latch member 2I to rotate in the same direction as the threaded portion' I4 of the shank.

As each latch member reaches its extreme clockwise position (shown in full lines in Fig. 3) further clockwise rotation of the manual operating knob I5EL will effect upward movement of lug 2Ig into engagement with the portion IIb of the Z-bar, and thereafter the relative movement between `the shank portion llc and member 2I` results in further compression of washer IS against the outer surface `of cover member I3 by bottom portion I5b of the knob and simultaneous pressure of the inner surface of cover member I3 against the peripheral gasket I2. The degree of pressure with which the inner surface of cover member I3 is engaged with gasket I2 will, of course, depend upon the degree of manual rotating pressure finally applied to the several knobs I5a; it being understood that the degree of dust-tightness of the gasketed parts may thus be controlled at will.

When it is desired to remove the cover member I3 it is only necessary to reverse the aforedescribed operation; the knobs I5* when first rotated counterclockwise permitting outward movement of cover member I3 to relieve the pressure of the latter against the gasket I2, and thereafter the members 2| are moved bodily inwardly until the lugs 2l'g thereof clear the portions IIb of the Z-bars. When such clearance is provided the latch members 2I are free respectively to rotate in a counterclockwise direction to the aforementioned extreme position indicated in dotted lines at 2 Ix in Fig. 3, in which position the lug 2|'g will clear the Z-bar. When all of the latch members 2I have been so positioned cover member I3 may be readily removed manur ally, one or more of the knobs I5 being used to pull or tilt the same outwardly from the peripheral wall, if necessary.

As will be apparent from Figs. 1 and 2, the arrangement is such that the manually operable portions I5a of the knobs are at all times accessible exteriorly of the open end of the casing.

It is to be understood thatin Fig. 4 we have illustrated use of the cover I3 for a casing or` housing for a control device of the automatically operable type, it being obvious that, if desired, the cover I3 may have attached thereto any suitable handle, pushbutton, or other operating member having a cooperative or interlocking relationship with a part of the switch or other control device enclosed within the housing.

In the modification of Fig. 5, the housing includes a peripheral wall designated 23, the opposite side and end portions of said peripheral wall' having Z-bars attached thereto, as indicated at 24 and 25. The gasket 26 which fits into the upwardly opening peripheral pocket formed by said Z-bars preferably'extends forwardly beyond the front edge portion 23a of said peripheral wall, inasmuch as the cover member 21 at all times overlies said front edge portion 23, and said cover member has a downwardly extending peripheral ange 21a which surrounds said peripheral wall. Cover 21 is hinged at one side thereof to the peripheral Awall 23 of the housing, as shown at 28 and 29; and said cover 21 is provided adjacent to the opposite side thereof with a single one of our improved latching devices, the knob'portions of which are shown at I5 and I5". The latching element of the character aforedescribed is adapted for cooperation with the horizontal portion of the adjacent Z-bar, and said single latching device is adapted to operate in the manner aforedescribed to effect releasable retention of cover 21 in closed position, the other elements of the latching device being adapted to function as aforedescribed to provide the desired degree of pressure of cover 21 against the dust-tighting gasket 26. As in the device of Figs. 1 to 4, the latching device of Fig. 5 is moved to clamping position and thereafter tightened as` an incident to clockwise movement of the knob I5, whereas the latch is loosened and the cover 21 released as an incident to counterclockwise movement of said knob.

Although the cover I3 of Fig. 4 is adapted for complete removal from the housing, it will be obvious to those skilled in the art that the same might be hinged at one side (say, the left-hand side) to the inner surface of one side wall of the housingthe opposite side of the cover being provided with one (as shown in Fig. 5) or more latching devices of the aforedescribed character to effect releasable closing and clamping of the cover in substantially the same manner as that heretofore mentioned.

As will be apparent from Figs. 4 and 5, our improved latching means has all portions thereof, except the operating knob, concealed, and thus the same provides a finished housing or casing and cover of neat and attractive appearance.

We claim:

1. In combination, a sheet metal switch casing having an open front end, a metal flange extending inwardly from the walls of said casing throughout the periphery of the latter and offset inwardly from said open end, a gasket seated upon said flange throughout the length of the latter, a sheet metal cover member adapted to overlie said gasketand to seat thereagainst, said cover member having at least one substantially circular opening formed therein adjacent to the periphery thereof but spaced inwardly therefrom to clear said flange, a device for securing said cover in closed position, said device including a manually operable knob forming the sole element thereof exposed at the outer sur- `face of said cover member, a metal shank eX- tending inwardly from said knob through said cover opening, said shankhaving a threaded inner end, a latch member having threaded engagement with said shank, said latch member being initially positioned a predetermined distance inwardly of said cover member and having an integral lug arranged at a rotary angle to permit passage thereof inwardly beyond the plane i of said flange, a metal washer slidably but nonrotatably carried by said shank at the inner surface of said cover member, a coiled spring interposed under compression between said washer and said latch member to provide a frictional rotary driving connection between said shank and said latch member, the arrangement being such that upon clockwise rotation of said knob said lug is moved clockwise to underlie said flange and thereafter said shank and said latch member are moved axially relatively to each other to'effect engagement of said lug with the inner surface of said flange and simultaneous compressing engagement of said cover member with said gasket, and said cover and said casing having cooperating elements at the side thereof opposite to said securing device to assist in retainingsaid cover in closed position.

2. In combination, a sheet metal switch casing having an open front end, a metal flange extending inwardly from the walls of said casing throughout the periphery of the latter and offset i inwardly from said open end, a gasket seated upon said ange throughout the length of the latter, a sheet metal cover member adapted to overlie said gasket and to seat thereagainst, said cover member having at least one substantially circular opening formed therein adjacent to the periphery thereof but spaced inwardly therefrom to clear said flange, a device for securing said cover in closed position, said device including a manually operable knob forming the sole element thereof exposed at the outer surface of `said cover member, a metal shank extending inwardly from said knob through said cover opening, said shank having a threaded inner end, a latch member having threaded engagement with said shank, said latch member being initially positioned a predetermined distance inwardly of said cover member and having an integral lug arranged at a rotary angle to permit passage thereof inwardly beyond the plane of said flange, said threaded inner end of the shank having an integral extension of reduced diameter, said extension having a peripheral groove formed therein, a notched washer adapted to fit within said groove, said washer acting to positively limit the degree of inward movement of said latch member, said latch member having axially extending surfaces arranged at an angle to each other, said cover member having an angle iron rigidly attached to the inner surface thereof and cooperating with said surfaces of the latch member to positively limit rotary movement of the latter in each direction, a metal washer slidably but non-rotatably carried by said shank at the inner surface of said cover member, a coiled spring interposed under compression between said last mentioned washer and said latch member to provide a frictional rotary driving connection between said shank and said latch member, the arrangement being such that upon clockwise rotation of said knob said lug is moved clockwise to underlie said .iiange and thereafter said shank and said latch member are moved axially relatively to each other to effect engagement of said lug with the inner surface of said flange and simultaneous compressing engagement of said cover member with said gasket, and said cover and said casing having cooperating elements at the side thereof opposite to said securing device to assist in retaining said cover in closed position.

3. In combination, a metal switch casing having an open front end, means providing a peripheral shoulder offset inwardly from saidkfront end, a cover member freely insertable into said opening and adapted to overlie said shoulder, said cover member having a multiplicity of substantially circular openings formed therein adjacent to the peripheral edge thereof but spaced inwardly therefrom to clear said shoulder, a

corresponding number of members for jointly securing said cover to said casing, said members having manually operable knobs forming the sole elements exposed at the front face of said cover member, a shank extending inwardly from each knob through one of said openings, said shank having a threaded inner end, a latch member having threaded engagement with said shank, a washer positively rotatable with said shank, a coiled spring interposed under compression between said washer and said latch member, and each latch member being initially positioned a predetermined distance inwardly of said cover member and having a lug arranged at a rotary angle to clear said shoulder, the arrangement being such that upon clockwise rotation of said knob said lug is frictionally moved clockwise, jointly with said shank, said Washer and said spring, to underlie said shoulder and thereafter said shank and said latch member are moved axially relatively to each other to effect clamping movement of said cover member and said lug toward the outer and inner surfaces of said shoulder.

4. In combination, a metal switch casing having an open front end, means providing a peripheral shoulder offset inwardly from said front end, a metal cover member freely insertable into said opening and adapted to overlie said shoulder, said cover member having a multiplicity of substantially circular openings formed therein adjacent to the peripheral edge thereof but spaced inwardly therefrom to clear said shoulder, a corresponding number of members for jointly securing said cover to said casing, said members having manually operable knobs forming the sole elements exposed at the front face of said. cover member, a shank extending inwardly from each knob through one of said openings, said shank having a threaded inner end, a latch member having threaded engagement with said shank, a washer positively rotatable with said shank, a coiled spring interposed under compression between said washer and said latch member, each latch member being initially positioned a predetermined distance inwardly of said cover member and having a lug arranged at a rotary angle to clear said shoulder, the arrangement being such that upon clockwise rotation of said knob said lug is frictionally moved clockwise, jointly with said shank, said washer and said spring, to underlie said shoulder and thereafter said shank and said latch member are moved axially relatively to each other to effect clamping movement of said cover member and said lug toward the outer and inner surfaces of said shoulder, and means comprising a gasket positioned upon the outer surface of said shoulder andagainst which said inserted cover member is drawn, for the purpose set forth.

5. As an article of manufacture, a metal cover member for electric switch enclosing'casings and the like, `said cover member having a plurality of relatively small substantially circular openings formed therein adjacent to peripheral edge portions thereof, a corresponding number of manually rotatable knobs having Shanks extending inwardly through the respective openings, said shanks each having a portion of polygonal form in transverse cross section adjacent to its respective knob and a screwthreaded inner end portion, a pair of washers arranged on opposite faces of said cover member and having openings to provide rotary clearance for said shank, at least one of said washers being non-metallic, a metal washer underlying the inner washer aforementioned, said metalwasher having a polygonal opening to kprovide for rotation thereof by said shank portion first mentioned, a coiled spring surrounding said shank and having its upper end engaged under compression at all times with said last mentioned washer, a metal latch member having anfupwardly opening pocket formed therein to accommodate the lower end portion of said spring, the bottom wall of said pockethavi-ng a tapped opening formed therein for cooperationwith said threaded shank portion, an `angle bar rigidly secured to the inner surface of said cover member, said latch member having angularly related sides cooperable with said barv to limit rotation of the former in each direction, a lug formed integrally with said latch member and extending therefrom in av horizontal plane in opposedrelation to said angularly related sides, said Vlatch member being initially spaced inwardly a predetermined distance from said cover member and adapted in its extreme counterclockwise position to provide for retracted positioning of said lug, the arrangement being such that upon clockwise rotation of said knob said latch is rst rotated to its extreme clockwise position to effect projection of said lug and thereafter said latch member is drawn axially of said shank to provide for yclamping engagement of said lug with an overhanging shoulder or the like.

6. In an enclosing casing for electrical control devices and the like, in combination, a metal housing member having an opening and peripheral walls surrounding said opening, a sheet metal bar of approximately Z-form in transverse cross section rigidly and permanently secured to each of said peripheral walls in inwardly offset relation to the forward ends of the latter in a manner to provide a forwardly opening peripheral pocket, a gasket positioned within said peripheral pocket and projecting forwardly of the latter, a flat metal cover member freely insertable into said opening in closely adjacent relationship to the peripheral walls of the latter and adapted to overlie said gasket, a plurality of manually operable latch members carried by said cover member, each of said latch members comprising a manually operable knob forming the sole element thereof exposed at the forward face of said cover member, said knob having a shank and said cover member having an opening to rotatably receive said shank, a composition washer interposed between said knob and the forward face of said cover member to form with said shank a substantially dust-tight closure for said cover opening, a latch element having a pocket formed therein and a tapped opening formed in the bottom wall of said pocket, said shank having a threaded portion adapted to cooperatively engage saidtapped opening, a coiled spring interposed under compression at all times between said bottom wall of the pocket and the inner surface of said cover member, said cover member having an angle bar welded to the inner surface thereof, said latch element having angularly arranged surfaces cooperable with said angle bar to limit the degree of ro-` tation of the former in each direction, and said latch element having a lug formed integrally with one side thereof, the arrangement being such that upon counterclockwise movement of said knob said lug is moved inwardly out of clamping engagement and then rotarily to a position to clear the lower surface of the horizontal portion of said Z-bar and said latch element is thereafter moved bodily inwardly of said shank, so that upon subsequent clockwise movement of said knob said lug is i'lrst moved into underlying relation to said lower surface of the horizontal portion of said Z-bar and thereafter into engagement with the latter, whereupon said shank moves inwardly relatively to said vlatch element to effect movement of said cover member into clamping engagement with said` peripheral gasket.

7. As an article of manufacture, a latching device adapted to be attached to the cover of an electrical switch housing or ythe like, said device comprising a manually rotatable Aknob forming the sole element thereof exposed upon the outer surface of the cover, a shank rigidly attached to said knob and projecting inwardly through an opening in the cover, the portion of said shank adjacent to said knob being of polygonal form in transverse cross section, a metal washer nonrotatably fitted onto said polygonal portion of the shank, a coiled spring the upper end of which is engaged under compression at all times with said washer, a latch member having an upwardly opening recess to accommodate the lower end of said spring, the bottom wall of said vrecess having a tapped opening formed therein, the lower end of said shank being threaded for cooperation with said tapped recess, said latch member having angularly related sides for cooperation with a suitable stop upon-the inner surface of the cover member to limit the angular degree of rotation of said latch member, said spring cooperating with said washer and said latch member to provide a relatively strong frictional rotary bias of said latch member between each of the extreme angular positions of the latter upon rotation of said shank in corresponding directions, said latch member having an integral laterally extending lug adapted for movement into and out of underlying relation to a shoulder formed on the switch housing, for the purpose set forth.

8. In an enclosing casing for electrical control devices and the like, in combination, a vertically mounted sheet metal housing including an open front end portion of rectangular contour, the opposed side and end walls of said front end portion having flanges extending inwardly therefrom in a common plane at right angles thereto and offset inwardly a substantial distance from the front edges thereof, a flat, punched sheet metal cover member of a size and contour closely approximating those of said open front, said cover member being adapted for assembly by seating the lower edge thereof against the lower end wall of said open front whereupon said cover member may be swung inwardly toward said flanges, said cover member having a plurality of substantially circular openings formed therein adjacent to the opposite vertical edges thereof but spaced inwardly from the latter to clear the respective side wall flanges, a corresponding number of members for jointly securing said cover member to said housing, said members having manually operable knobs forming the sole elements exposed at the front face of said cover member, a shank extending inwardly from each knob through one of said openings, said shank having a threaded inner end, a latch member having threaded engagement with said shank, each latch member being initially positioned a predetermined distance inwardly of said cover member and having a lug arranged at a rotary angle to clear the adjacent flange, a washer slidably but non-rotatably carried by each shank, a. coiled spring interposed under compression between said Washer and said latch member, whereby upon clockwise rotation of each knob the associated latch lug is moved clockwise to underlie the adjacent ange, and whereby upon further clockwise movement of said knobs the associated Shanks and latch members are moved axially relatively to each other to effect movement of said cover member toward the respective flanges.

9. In an enclosing casing for electrical control devices and the like, in combination, a vertically mounted sheet metal housing including an open front end portion of rectangular contour, the opposed side and end walls ofl said frontend portion having flanges extending inwardly therefrom in a common plane at right angles thereto and offset inwardly a substantial distance from the front edges thereof, a at, punched `sheet metal cover member of a size and contour closely approximating those of said open front, said cover member being adapted for assembly by seating the lowerv edge thereof against the lowervend wall of said open front whereupon said cover member may be swung inwardly toward said Ilanges, said cover member having a plurality of substantially circular openings formed therein adjacent to the opposite vertical edges thereof but spaced inwardly from the latter to clear -the respective side wall flanges, a corresponding number of members for jointly securing said cover member to said housing, said members having manually operable knobs forming the sole elements exposed at the front face of said cover member, a shank extending inwardly from each knob through one of said openings, said shank having a threaded inner end, a latch member having threaded engagement with said shank, each latch member being initially positioned a predetermined distance inwardly of said coverv member and having a lug arranged at a rotary angle to clear the adjacent ange, a washer slidably but non-rotatably carried by each shank, a coiled spring interposed under compression between said washer and said latch member, whereby upon clockwise rotation of each knob the associated latch lug is moved clockwise to underlie the adjacent llange, whereby upon further clockwise movement of said knobs the associated shanks and latch members are moved axially relatively to each other to effect movement of said cover member toward the respective flanges, felt washers surrounding the respective shanks and interposed between said knobs and the outer surface of said cover member, and a felt gasket seated upon the respective flanges, whereby said enclosing casing is rendered substantially dust-tight, the arrangement of the aforementioned parts being such that the manually engageable portions of said knobs are at all times positioned forwardly of the front edge portions of said housing.

HERMAN J. KOCH. ANTHONY A. KRAUS. 

